include/__functional/bind.h - llvm-project/libcxx - Git at Google

 // -*- C++ -*-
 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//

 #ifndef _LIBCPP___FUNCTIONAL_BIND_H
 #define _LIBCPP___FUNCTIONAL_BIND_H

 #include <__config>
 #include <__functional/invoke.h>
 #include <__functional/weak_result_type.h>
 #include <__fwd/functional.h>
 #include <__type_traits/decay.h>
 #include <__type_traits/is_reference_wrapper.h>
 #include <__type_traits/is_void.h>
 #include <cstddef>
 #include <tuple>

 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
 #endif

 _LIBCPP_BEGIN_NAMESPACE_STD

 template <class _Tp>
 struct is_bind_expression
     : _If< _IsSame<_Tp, __remove_cvref_t<_Tp> >::value, false_type, is_bind_expression<__remove_cvref_t<_Tp> > > {};

 #if _LIBCPP_STD_VER >= 17
 template <class _Tp>
 inline constexpr bool is_bind_expression_v = is_bind_expression<_Tp>::value;
 #endif

 template <class _Tp>
 struct is_placeholder
     : _If< _IsSame<_Tp, __remove_cvref_t<_Tp> >::value,
            integral_constant<int, 0>,
            is_placeholder<__remove_cvref_t<_Tp> > > {};

 #if _LIBCPP_STD_VER >= 17
 template <class _Tp>
 inline constexpr int is_placeholder_v = is_placeholder<_Tp>::value;
 #endif

 namespace placeholders {

 template <int _Np>
 struct __ph {};

 // C++17 recommends that we implement placeholders as `inline constexpr`, but allows
 // implementing them as `extern <implementation-defined>`. Libc++ implements them as
 // `extern const` in all standard modes to avoid an ABI break in C++03: making them
 // `inline constexpr` requires removing their definition in the shared library to
 // avoid ODR violations, which is an ABI break.
 //
 // In practice, since placeholders are empty, `extern const` is almost impossible
 // to distinguish from `inline constexpr` from a usage stand point.
 _LIBCPP_EXPORTED_FROM_ABI extern const __ph<1> _1;
 _LIBCPP_EXPORTED_FROM_ABI extern const __ph<2> _2;
 _LIBCPP_EXPORTED_FROM_ABI extern const __ph<3> _3;
 _LIBCPP_EXPORTED_FROM_ABI extern const __ph<4> _4;
 _LIBCPP_EXPORTED_FROM_ABI extern const __ph<5> _5;
 _LIBCPP_EXPORTED_FROM_ABI extern const __ph<6> _6;
 _LIBCPP_EXPORTED_FROM_ABI extern const __ph<7> _7;
 _LIBCPP_EXPORTED_FROM_ABI extern const __ph<8> _8;
 _LIBCPP_EXPORTED_FROM_ABI extern const __ph<9> _9;
 _LIBCPP_EXPORTED_FROM_ABI extern const __ph<10> _10;

 } // namespace placeholders

 template <int _Np>
 struct is_placeholder<placeholders::__ph<_Np> > : public integral_constant<int, _Np> {};

 #ifndef _LIBCPP_CXX03_LANG

 template <class _Tp, class _Uj>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp& __mu(reference_wrapper<_Tp> __t, _Uj&) {
   return __t.get();
 }

 template <class _Ti, class... _Uj, size_t... _Indx>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 typename __invoke_of<_Ti&, _Uj...>::type
 __mu_expand(_Ti& __ti, tuple<_Uj...>& __uj, __tuple_indices<_Indx...>) {
   return __ti(std::forward<_Uj>(std::get<_Indx>(__uj))...);
 }

 template <class _Ti, class... _Uj, __enable_if_t<is_bind_expression<_Ti>::value, int> = 0>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 typename __invoke_of<_Ti&, _Uj...>::type
 __mu(_Ti& __ti, tuple<_Uj...>& __uj) {
   typedef typename __make_tuple_indices<sizeof...(_Uj)>::type __indices;
   return std::__mu_expand(__ti, __uj, __indices());
 }

 template <bool IsPh, class _Ti, class _Uj>
 struct __mu_return2 {};

 template <class _Ti, class _Uj>
 struct __mu_return2<true, _Ti, _Uj> {
   typedef typename tuple_element<is_placeholder<_Ti>::value - 1, _Uj>::type type;
 };

 template <class _Ti, class _Uj, __enable_if_t<0 < is_placeholder<_Ti>::value, int> = 0>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
     typename __mu_return2<0 < is_placeholder<_Ti>::value, _Ti, _Uj>::type
     __mu(_Ti&, _Uj& __uj) {
   const size_t __indx = is_placeholder<_Ti>::value - 1;
   return std::forward<typename tuple_element<__indx, _Uj>::type>(std::get<__indx>(__uj));
 }

 template <class _Ti,
           class _Uj,
           __enable_if_t<!is_bind_expression<_Ti>::value && is_placeholder<_Ti>::value == 0 &&
                             !__is_reference_wrapper<_Ti>::value,
                         int> = 0>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Ti& __mu(_Ti& __ti, _Uj&) {
   return __ti;
 }

 template <class _Ti, bool IsReferenceWrapper, bool IsBindEx, bool IsPh, class _TupleUj>
 struct __mu_return_impl;

 template <bool _Invokable, class _Ti, class... _Uj>
 struct __mu_return_invokable // false
 {
   typedef __nat type;
 };

 template <class _Ti, class... _Uj>
 struct __mu_return_invokable<true, _Ti, _Uj...> {
   typedef typename __invoke_of<_Ti&, _Uj...>::type type;
 };

 template <class _Ti, class... _Uj>
 struct __mu_return_impl<_Ti, false, true, false, tuple<_Uj...> >
     : public __mu_return_invokable<__invokable<_Ti&, _Uj...>::value, _Ti, _Uj...> {};

 template <class _Ti, class _TupleUj>
 struct __mu_return_impl<_Ti, false, false, true, _TupleUj> {
   typedef typename tuple_element<is_placeholder<_Ti>::value - 1, _TupleUj>::type&& type;
 };

 template <class _Ti, class _TupleUj>
 struct __mu_return_impl<_Ti, true, false, false, _TupleUj> {
   typedef typename _Ti::type& type;
 };

 template <class _Ti, class _TupleUj>
 struct __mu_return_impl<_Ti, false, false, false, _TupleUj> {
   typedef _Ti& type;
 };

 template <class _Ti, class _TupleUj>
 struct __mu_return
     : public __mu_return_impl<
           _Ti,
           __is_reference_wrapper<_Ti>::value,
           is_bind_expression<_Ti>::value,
           0 < is_placeholder<_Ti>::value && is_placeholder<_Ti>::value <= tuple_size<_TupleUj>::value,
           _TupleUj> {};

 template <class _Fp, class _BoundArgs, class _TupleUj>
 struct __is_valid_bind_return {
   static const bool value = false;
 };

 template <class _Fp, class... _BoundArgs, class _TupleUj>
 struct __is_valid_bind_return<_Fp, tuple<_BoundArgs...>, _TupleUj> {
   static const bool value = __invokable<_Fp, typename __mu_return<_BoundArgs, _TupleUj>::type...>::value;
 };

 template <class _Fp, class... _BoundArgs, class _TupleUj>
 struct __is_valid_bind_return<_Fp, const tuple<_BoundArgs...>, _TupleUj> {
   static const bool value = __invokable<_Fp, typename __mu_return<const _BoundArgs, _TupleUj>::type...>::value;
 };

 template <class _Fp, class _BoundArgs, class _TupleUj, bool = __is_valid_bind_return<_Fp, _BoundArgs, _TupleUj>::value>
 struct __bind_return;

 template <class _Fp, class... _BoundArgs, class _TupleUj>
 struct __bind_return<_Fp, tuple<_BoundArgs...>, _TupleUj, true> {
   typedef typename __invoke_of< _Fp&, typename __mu_return< _BoundArgs, _TupleUj >::type... >::type type;
 };

 template <class _Fp, class... _BoundArgs, class _TupleUj>
 struct __bind_return<_Fp, const tuple<_BoundArgs...>, _TupleUj, true> {
   typedef typename __invoke_of< _Fp&, typename __mu_return< const _BoundArgs, _TupleUj >::type... >::type type;
 };

 template <class _Fp, class _BoundArgs, size_t... _Indx, class _Args>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 typename __bind_return<_Fp, _BoundArgs, _Args>::type
 __apply_functor(_Fp& __f, _BoundArgs& __bound_args, __tuple_indices<_Indx...>, _Args&& __args) {
   return std::__invoke(__f, std::__mu(std::get<_Indx>(__bound_args), __args)...);
 }

 template <class _Fp, class... _BoundArgs>
 class __bind : public __weak_result_type<__decay_t<_Fp> > {
 protected:
   using _Fd = __decay_t<_Fp>;
   typedef tuple<__decay_t<_BoundArgs>...> _Td;

 private:
   _Fd __f_;
   _Td __bound_args_;

   typedef typename __make_tuple_indices<sizeof...(_BoundArgs)>::type __indices;

 public:
   template <
       class _Gp,
       class... _BA,
       __enable_if_t<is_constructible<_Fd, _Gp>::value && !is_same<__libcpp_remove_reference_t<_Gp>, __bind>::value,
                     int> = 0>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit __bind(_Gp&& __f, _BA&&... __bound_args)
       : __f_(std::forward<_Gp>(__f)), __bound_args_(std::forward<_BA>(__bound_args)...) {}

   template <class... _Args>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 typename __bind_return<_Fd, _Td, tuple<_Args&&...> >::type
   operator()(_Args&&... __args) {
     return std::__apply_functor(__f_, __bound_args_, __indices(), tuple<_Args&&...>(std::forward<_Args>(__args)...));
   }

   template <class... _Args>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
       typename __bind_return<const _Fd, const _Td, tuple<_Args&&...> >::type
       operator()(_Args&&... __args) const {
     return std::__apply_functor(__f_, __bound_args_, __indices(), tuple<_Args&&...>(std::forward<_Args>(__args)...));
   }
 };

 template <class _Fp, class... _BoundArgs>
 struct is_bind_expression<__bind<_Fp, _BoundArgs...> > : public true_type {};

 template <class _Rp, class _Fp, class... _BoundArgs>
 class __bind_r : public __bind<_Fp, _BoundArgs...> {
   typedef __bind<_Fp, _BoundArgs...> base;
   typedef typename base::_Fd _Fd;
   typedef typename base::_Td _Td;

 public:
   typedef _Rp result_type;

   template <
       class _Gp,
       class... _BA,
       __enable_if_t<is_constructible<_Fd, _Gp>::value && !is_same<__libcpp_remove_reference_t<_Gp>, __bind_r>::value,
                     int> = 0>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit __bind_r(_Gp&& __f, _BA&&... __bound_args)
       : base(std::forward<_Gp>(__f), std::forward<_BA>(__bound_args)...) {}

   template <
       class... _Args,
       __enable_if_t<is_convertible<typename __bind_return<_Fd, _Td, tuple<_Args&&...> >::type, result_type>::value ||
                         is_void<_Rp>::value,
                     int> = 0>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 result_type operator()(_Args&&... __args) {
     typedef __invoke_void_return_wrapper<_Rp> _Invoker;
     return _Invoker::__call(static_cast<base&>(*this), std::forward<_Args>(__args)...);
   }

   template <class... _Args,
             __enable_if_t<is_convertible<typename __bind_return<const _Fd, const _Td, tuple<_Args&&...> >::type,
                                          result_type>::value ||
                               is_void<_Rp>::value,
                           int> = 0>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 result_type operator()(_Args&&... __args) const {
     typedef __invoke_void_return_wrapper<_Rp> _Invoker;
     return _Invoker::__call(static_cast<base const&>(*this), std::forward<_Args>(__args)...);
   }
 };

 template <class _Rp, class _Fp, class... _BoundArgs>
 struct is_bind_expression<__bind_r<_Rp, _Fp, _BoundArgs...> > : public true_type {};

 template <class _Fp, class... _BoundArgs>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __bind<_Fp, _BoundArgs...>
 bind(_Fp&& __f, _BoundArgs&&... __bound_args) {
   typedef __bind<_Fp, _BoundArgs...> type;
   return type(std::forward<_Fp>(__f), std::forward<_BoundArgs>(__bound_args)...);
 }

 template <class _Rp, class _Fp, class... _BoundArgs>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __bind_r<_Rp, _Fp, _BoundArgs...>
 bind(_Fp&& __f, _BoundArgs&&... __bound_args) {
   typedef __bind_r<_Rp, _Fp, _BoundArgs...> type;
   return type(std::forward<_Fp>(__f), std::forward<_BoundArgs>(__bound_args)...);
 }

 #endif // _LIBCPP_CXX03_LANG

 _LIBCPP_END_NAMESPACE_STD

 #endif // _LIBCPP___FUNCTIONAL_BIND_H
	// -- C++ --
	//===----------------------------------------------------------------------===//
	//
	// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
	// See https://llvm.org/LICENSE.txt for license information.
	// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
	//
	//===----------------------------------------------------------------------===//

	#ifndef _LIBCPP___FUNCTIONAL_BIND_H
	#define _LIBCPP___FUNCTIONAL_BIND_H

	#include <__config>
	#include <__functional/invoke.h>
	#include <__functional/weak_result_type.h>
	#include <__fwd/functional.h>
	#include <__type_traits/decay.h>
	#include <__type_traits/is_reference_wrapper.h>
	#include <__type_traits/is_void.h>
	#include <cstddef>
	#include <tuple>

	#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
	# pragma GCC system_header
	#endif

	_LIBCPP_BEGIN_NAMESPACE_STD

	template <class _Tp>
	struct is_bind_expression
	: _If< _IsSame<_Tp, __remove_cvref_t<_Tp> >::value, false_type, is_bind_expression<__remove_cvref_t<_Tp> > > {};

	#if _LIBCPP_STD_VER >= 17
	template <class _Tp>
	inline constexpr bool is_bind_expression_v = is_bind_expression<_Tp>::value;
	#endif

	template <class _Tp>
	struct is_placeholder
	: _If< _IsSame<_Tp, __remove_cvref_t<_Tp> >::value,
	integral_constant<int, 0>,
	is_placeholder<__remove_cvref_t<_Tp> > > {};

	#if _LIBCPP_STD_VER >= 17
	template <class _Tp>
	inline constexpr int is_placeholder_v = is_placeholder<_Tp>::value;
	#endif

	namespace placeholders {

	template <int _Np>
	struct __ph {};

	// C++17 recommends that we implement placeholders as `inline constexpr`, but allows
	// implementing them as `extern <implementation-defined>`. Libc++ implements them as
	// `extern const` in all standard modes to avoid an ABI break in C++03: making them
	// `inline constexpr` requires removing their definition in the shared library to
	// avoid ODR violations, which is an ABI break.
	//
	// In practice, since placeholders are empty, `extern const` is almost impossible
	// to distinguish from `inline constexpr` from a usage stand point.
	_LIBCPP_EXPORTED_FROM_ABI extern const __ph<1> _1;
	_LIBCPP_EXPORTED_FROM_ABI extern const __ph<2> _2;
	_LIBCPP_EXPORTED_FROM_ABI extern const __ph<3> _3;
	_LIBCPP_EXPORTED_FROM_ABI extern const __ph<4> _4;
	_LIBCPP_EXPORTED_FROM_ABI extern const __ph<5> _5;
	_LIBCPP_EXPORTED_FROM_ABI extern const __ph<6> _6;
	_LIBCPP_EXPORTED_FROM_ABI extern const __ph<7> _7;
	_LIBCPP_EXPORTED_FROM_ABI extern const __ph<8> _8;
	_LIBCPP_EXPORTED_FROM_ABI extern const __ph<9> _9;
	_LIBCPP_EXPORTED_FROM_ABI extern const __ph<10> _10;

	} // namespace placeholders

	template <int _Np>
	struct is_placeholder<placeholders::__ph<_Np> > : public integral_constant<int, _Np> {};

	#ifndef _LIBCPP_CXX03_LANG

	template <class _Tp, class _Uj>
	inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp& __mu(reference_wrapper<_Tp> __t, _Uj&) {
	return __t.get();
	}

	template <class _Ti, class... _Uj, size_t... _Indx>
	inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 typename __invoke_of<_Ti&, _Uj...>::type
	__mu_expand(_Ti& __ti, tuple<_Uj...>& __uj, __tuple_indices<_Indx...>) {
	return __ti(std::forward<_Uj>(std::get<_Indx>(__uj))...);
	}

	template <class _Ti, class... _Uj, __enable_if_t<is_bind_expression<_Ti>::value, int> = 0>
	inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 typename __invoke_of<_Ti&, _Uj...>::type
	__mu(_Ti& __ti, tuple<_Uj...>& __uj) {
	typedef typename __make_tuple_indices<sizeof...(_Uj)>::type __indices;
	return std::__mu_expand(__ti, __uj, __indices());
	}

	template <bool IsPh, class _Ti, class _Uj>
	struct __mu_return2 {};

	template <class _Ti, class _Uj>
	struct __mu_return2<true, _Ti, _Uj> {
	typedef typename tuple_element<is_placeholder<_Ti>::value - 1, _Uj>::type type;
	};

	template <class _Ti, class _Uj, __enable_if_t<0 < is_placeholder<_Ti>::value, int> = 0>
	inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
	typename __mu_return2<0 < is_placeholder<_Ti>::value, _Ti, _Uj>::type
	__mu(_Ti&, _Uj& __uj) {
	const size_t __indx = is_placeholder<_Ti>::value - 1;
	return std::forward<typename tuple_element<__indx, _Uj>::type>(std::get<__indx>(__uj));
	}

	template <class _Ti,
	class _Uj,
	__enable_if_t<!is_bind_expression<_Ti>::value && is_placeholder<_Ti>::value == 0 &&
	!__is_reference_wrapper<_Ti>::value,
	int> = 0>
	inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Ti& __mu(_Ti& __ti, _Uj&) {
	return __ti;
	}

	template <class _Ti, bool IsReferenceWrapper, bool IsBindEx, bool IsPh, class _TupleUj>
	struct __mu_return_impl;

	template <bool _Invokable, class _Ti, class... _Uj>
	struct __mu_return_invokable // false
	{
	typedef __nat type;
	};

	template <class _Ti, class... _Uj>
	struct __mu_return_invokable<true, _Ti, _Uj...> {
	typedef typename __invoke_of<_Ti&, _Uj...>::type type;
	};

	template <class _Ti, class... _Uj>
	struct __mu_return_impl<_Ti, false, true, false, tuple<_Uj...> >
	: public __mu_return_invokable<__invokable<_Ti&, _Uj...>::value, _Ti, _Uj...> {};

	template <class _Ti, class _TupleUj>
	struct __mu_return_impl<_Ti, false, false, true, _TupleUj> {
	typedef typename tuple_element<is_placeholder<_Ti>::value - 1, _TupleUj>::type&& type;
	};

	template <class _Ti, class _TupleUj>
	struct __mu_return_impl<_Ti, true, false, false, _TupleUj> {
	typedef typename _Ti::type& type;
	};

	template <class _Ti, class _TupleUj>
	struct __mu_return_impl<_Ti, false, false, false, _TupleUj> {
	typedef _Ti& type;
	};

	template <class _Ti, class _TupleUj>
	struct __mu_return
	: public __mu_return_impl<
	_Ti,
	__is_reference_wrapper<_Ti>::value,
	is_bind_expression<_Ti>::value,
	0 < is_placeholder<_Ti>::value && is_placeholder<_Ti>::value <= tuple_size<_TupleUj>::value,
	_TupleUj> {};

	template <class _Fp, class _BoundArgs, class _TupleUj>
	struct __is_valid_bind_return {
	static const bool value = false;
	};

	template <class _Fp, class... _BoundArgs, class _TupleUj>
	struct __is_valid_bind_return<_Fp, tuple<_BoundArgs...>, _TupleUj> {
	static const bool value = __invokable<_Fp, typename __mu_return<_BoundArgs, _TupleUj>::type...>::value;
	};

	template <class _Fp, class... _BoundArgs, class _TupleUj>
	struct __is_valid_bind_return<_Fp, const tuple<_BoundArgs...>, _TupleUj> {
	static const bool value = __invokable<_Fp, typename __mu_return<const _BoundArgs, _TupleUj>::type...>::value;
	};

	template <class _Fp, class _BoundArgs, class _TupleUj, bool = __is_valid_bind_return<_Fp, _BoundArgs, _TupleUj>::value>
	struct __bind_return;

	template <class _Fp, class... _BoundArgs, class _TupleUj>
	struct __bind_return<_Fp, tuple<_BoundArgs...>, _TupleUj, true> {
	typedef typename __invoke_of< _Fp&, typename __mu_return< _BoundArgs, _TupleUj >::type... >::type type;
	};

	template <class _Fp, class... _BoundArgs, class _TupleUj>
	struct __bind_return<_Fp, const tuple<_BoundArgs...>, _TupleUj, true> {
	typedef typename __invoke_of< _Fp&, typename __mu_return< const _BoundArgs, _TupleUj >::type... >::type type;
	};

	template <class _Fp, class _BoundArgs, size_t... _Indx, class _Args>
	inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 typename __bind_return<_Fp, _BoundArgs, _Args>::type
	__apply_functor(_Fp& __f, _BoundArgs& __bound_args, __tuple_indices<_Indx...>, _Args&& __args) {
	return std::__invoke(__f, std::__mu(std::get<_Indx>(__bound_args), __args)...);
	}

	template <class _Fp, class... _BoundArgs>
	class __bind : public __weak_result_type<__decay_t<_Fp> > {
	protected:
	using _Fd = __decay_t<_Fp>;
	typedef tuple<__decay_t<_BoundArgs>...> _Td;

	private:
	_Fd __f_;
	_Td __bound_args_;

	typedef typename __make_tuple_indices<sizeof...(_BoundArgs)>::type __indices;

	public:
	template <
	class _Gp,
	class... _BA,
	__enable_if_t<is_constructible<_Fd, _Gp>::value && !is_same<__libcpp_remove_reference_t<_Gp>, __bind>::value,
	int> = 0>
	_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit __bind(_Gp&& __f, _BA&&... __bound_args)
	: __f_(std::forward<_Gp>(__f)), __bound_args_(std::forward<_BA>(__bound_args)...) {}

	template <class... _Args>
	_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 typename __bind_return<_Fd, _Td, tuple<_Args&&...> >::type
	operator()(_Args&&... __args) {
	return std::__apply_functor(__f_, __bound_args_, __indices(), tuple<_Args&&...>(std::forward<_Args>(__args)...));
	}

	template <class... _Args>
	_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
	typename __bind_return<const _Fd, const _Td, tuple<_Args&&...> >::type
	operator()(_Args&&... __args) const {
	return std::__apply_functor(__f_, __bound_args_, __indices(), tuple<_Args&&...>(std::forward<_Args>(__args)...));
	}
	};

	template <class _Fp, class... _BoundArgs>
	struct is_bind_expression<__bind<_Fp, _BoundArgs...> > : public true_type {};

	template <class _Rp, class _Fp, class... _BoundArgs>
	class __bind_r : public __bind<_Fp, _BoundArgs...> {
	typedef __bind<_Fp, _BoundArgs...> base;
	typedef typename base::_Fd _Fd;
	typedef typename base::_Td _Td;

	public:
	typedef _Rp result_type;

	template <
	class _Gp,
	class... _BA,
	__enable_if_t<is_constructible<_Fd, _Gp>::value && !is_same<__libcpp_remove_reference_t<_Gp>, __bind_r>::value,
	int> = 0>
	_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit __bind_r(_Gp&& __f, _BA&&... __bound_args)
	: base(std::forward<_Gp>(__f), std::forward<_BA>(__bound_args)...) {}

	template <
	class... _Args,
	__enable_if_t<is_convertible<typename __bind_return<_Fd, _Td, tuple<_Args&&...> >::type, result_type>::value \|\|
	is_void<_Rp>::value,
	int> = 0>
	_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 result_type operator()(_Args&&... __args) {
	typedef __invoke_void_return_wrapper<_Rp> _Invoker;
	return _Invoker::__call(static_cast<base&>(*this), std::forward<_Args>(__args)...);
	}

	template <class... _Args,
	__enable_if_t<is_convertible<typename __bind_return<const _Fd, const _Td, tuple<_Args&&...> >::type,
	result_type>::value \|\|
	is_void<_Rp>::value,
	int> = 0>
	_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 result_type operator()(_Args&&... __args) const {
	typedef __invoke_void_return_wrapper<_Rp> _Invoker;
	return _Invoker::__call(static_cast<base const&>(*this), std::forward<_Args>(__args)...);
	}
	};

	template <class _Rp, class _Fp, class... _BoundArgs>
	struct is_bind_expression<__bind_r<_Rp, _Fp, _BoundArgs...> > : public true_type {};

	template <class _Fp, class... _BoundArgs>
	inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __bind<_Fp, _BoundArgs...>
	bind(_Fp&& __f, _BoundArgs&&... __bound_args) {
	typedef __bind<_Fp, _BoundArgs...> type;
	return type(std::forward<_Fp>(__f), std::forward<_BoundArgs>(__bound_args)...);
	}

	template <class _Rp, class _Fp, class... _BoundArgs>
	inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __bind_r<_Rp, _Fp, _BoundArgs...>
	bind(_Fp&& __f, _BoundArgs&&... __bound_args) {
	typedef __bind_r<_Rp, _Fp, _BoundArgs...> type;
	return type(std::forward<_Fp>(__f), std::forward<_BoundArgs>(__bound_args)...);
	}

	#endif // _LIBCPP_CXX03_LANG

	_LIBCPP_END_NAMESPACE_STD

	#endif // _LIBCPP___FUNCTIONAL_BIND_H